Articles of polyvinyl alcohol having improved dyeability



f rods, and the like.

Unite States Patent fificc 3,053,605 Patented Sept. 11, 1962 3,053,605ARTICLES F POLYVENYL ALCOHOL HAVING IMPROVED DYEABILITY Kenichi Tanabe,Kurashiki City, and Kanji Matsubayashi, Mizue, Kurashiki City, Japan,assignors of three-fourths to Kurashiki Rayon Co., Ltd., Okayoma, Japan,a corporation of Japan, and one-fourth to Air Reduction CompanyIncorporated, New York, N.Y., a corporation of New York No Drawing.Filed May 20, 1959, Ser. No. 814,367

Claims priority, application Japan May 26, 1958 8 Claims. (Cl. 8-1155)This invention relates to the production of shaped articles of polyvinylalcohol having improved dyeability. The invention is especiallyconcerned with the production of polyvinyl alcohol filaments havingimproved dyeing properties.

Polyvinyl alcohol shaped articles such as filaments and films areproduced by known methods. Usually such shaped articles show undesirablesensitivity to water, especially hot water. In order to improve theproperties of shaped articles such as filaments, the articles areusually subjected to a heat treatment at temperatures in the range of200250 C. followed by acetalization as with formaldehyde.

Polyvinyl alcohol shaped articles treated as above have inferior dyeingcharacteristics. Both heat treatment and subsequent acetalization have adeleterious effect on dyeability of the shaped articles.

It is an object of this invention to provide a method for the productionof shaped articles of polyvinyl alcohol characterized by improved dyeingproperties.

It is a further object of the invention to produce polyvinyl alcoholfilaments of improved dyeability.

Other objects will be apparent from the following description of theinvention.

In carrying out the present invention, polyvinyl alcohol shaped articlesare oxidized to convert some of the hydroxyl groups to carbonyl groups.After oxidation, the oxidized article is reacted with ammonia or aprimary or secondary amine and with hydrogen cyanide or an inorganiccyanide salt. Through this combination of treating steps, basic nitrogengroups are introduced into the polyvinyl alcohol shaped article, and thethusly treated shaped article has greatly improved dyeing properties.

Polyvinyl alcohol shaped articles which are treated in accordance withthis invention are prepared by known methods. By shaped articles aremeant filaments, films, An especially preferred method for preparingfilaments which are to be treated in accordance with this invention isdescribed in Tomonari et al. application Serial No. 336,166, filedFebruary 10, 1953. Other methods can be employed.

The polyvinyl alcohol shaped article is first treated in the process ofthis invention to oxidize some of the hy- 2. acid salts, and hydrogenperoxide together with pervanadic acid, and the like.

It is generally preferred to carry out the oxidation by immersing thepolyvinyl alcohol shaped article in an aqueous solution of the oxidizingagent. However, the oxidation can be carried out in organic solventsolutions of oxidizing agent or using gaseous oxidizing agents. Theoxidation can be carried out at normal or elevated temperatures, e.g.0100 C., for times ranging from a few minutes to several hours.

It is necessary in accordance with the invention to oxidize sufiicientof the polyvinyl alcohol hydroxyl groups so that after subsequent amineand cyanide treatment the shaped article has good dyeingcharacteristics. Generally oxidation of about 0.1 to 20% of the hydroxylgroups and usually about 0.2 to 10% is preferred.

After oxidation, the shaped polyvinyl alcohol article is reacted withammonia or a primary or secondary amine and with hydrogen cyanide or acyanide salt. The reaction is believed to proceed as follows:

Besides ammonia, examples of primary and secondary amines which can beused include methyl amine, ethyl amine, Z-ethyl hexylamine, laurylamine,cyclohexylamine, benzylamine, ethanol amine, glycine, alanine, glutamicacid, w-amino caproic acid, taurine, dimethyl amine, diethyl amine,lauryl methyl amine, piperidine, diethanol amine, morpohline, andsarcosine, as well as diamines and polyamines such as ethylene diamine,tetramethylene diamine, hexamethylene diamine, piperazine, triethylenetetramine, polyethylene polyamine, polyethylene imine, and the like.Salts of ammonia and the amines such as hydrochloric acid, sulfuricacid, phosphoric acid, hypophosphoric acid, acid sulfite, alkali carbonate, formic acid and acetic acid salts can be used.

Cyanides which are used include hydrogen cyanide and alkali or alkalineearth metal salts thereof such as sodium cyanide, potassium cyanide,calcium cyanide, and the like.

The reaction of the oxidized polyvinyl alcohol shaped article with amineand cyanide is preferably carried out by immersing the shaped article inan aqueous solution or a water-alcohol solution containing 150% byWeight of a mixture of droxyl groups to carbonyl groups. The oxidationcan be before or after other treating steps such as heat treatment oracetalization. Suitable oxidizing agents include hypochlorous acid,chlorous acid, alkali metal chlorites and hypochlorites, calciumchlorites and hypochlorites (ineluding bleaching powders), nitric acid,hyponitric acid,

(a) An amine or ammonia together with a molar equiv-, alent or less ofhydrogen cyanide, or

(b) A salt of ammonia or an amine together with a molar equivalentamount of a cyanide salt, or

(c) A salt of ammonia or an amine together with a molar equivalentamount of a cyanide salt, and excess am monia or amine.

Reaction times of several minutes to many hours, usually about 5 minutesto 2 hours at temperature of 0100 0., usually 20-70" C., are employed.The oxidized shaped articles need not be reacted simultaneously with theamine and cyanide. Alternatively, the oxidized article can be separatelyreacted with amine and cyanide in either order. Vapor phase reactions ofthe oxidized polyvinyl alcohol article with the arnine and cyanide canbe employed. Y

The treated polyvinyl alcohol shaped articles can be subjected to knowntreating steps such as heat treatment and acetalization to furtherimprove properties thereof. These treating steps can be carried outbefore or after the various process steps of this invention.

The shaped polyvinyl alcohol articles produced by this invention havegreatly improved dyeing characteristics. These articles are readily dyedto a deep color with both acid type dyes and direct dyestuffs. The basicnitrogen 3 groups introduced into the shaped article are highly stableagainst acid, alkali and hot water.

Dyeability of filaments produced by this invention is greatly superiorto that of cotton fibers with direct dyes. With acidic dyes and mordantdyes, the dyeability is comparable with that of wool fibers. Both theamino and cyano radicals introduced by the instant process are believedto contribute to the improved product dyeability.

The polyvinyl alcohol articles treated by the present process arepreferably composed substantially completely of polyvinyl alcohol.However, copolymers of vinyl alcohol with up to about 20% of othercompounds such as ethylene, maleic anhydride, and the like can be used.

The following examples illustrate the invention:

EXAMPLE 1 Polyvinyl alcohol filaments were prepared by wet spinning. Thefilaments were heat treated for 3 seconds at 235 C.

Portion 1 of the filaments was treated for 1 hour at 60 C. in an aqueoussolution containing by weight 0.5% N-bromosuccinimide, 0.23% pyridine,and 15% sodium sulfate.

Portion 2 of the filaments was treated for 1 hour at 60 C. in an aqueoussolution containing by weight 2% hydrogen peroxide and 15% sodiumsulfate.

Portion 3 of the filaments was not oxidized.

Portions l and 2 each were treated for 30 minutes at 60 C. in an aqueoussolution containing by weight 2% ethylene diamine monohydrochloric acidsalt and 1% sodium cyanide.

Portions l, 2 and 3 were formalized for 1 hour at 70 C. in an aqueoussolution containing by weight formaldehyde, 15% sulfuric acid, and 15%sodium sulfate.

The following table shows the results obtained:

Table 1 Portion No 1 2 3 Weight percent nitrogen after treatment withamine 1 Dyed 1 hour at 70 C. in aqueous bath containing Nippon FastVioet BB in amount of 2% by weight of filament.

These results show the improvement in dyeing properties of filamentstreated by the invention. Filament strength decreased only slightlythrough practice of the invention.

EXAMPLE 2 Polyvinyl alcohol film was formed -by known tech niques. Thefilm was treated for 1 hour at 50 C. in an aqueous solution containingby weight 20% persulfuric acid and 20% sodium sulfate under tension.Then the film was treated under tension for 2 hours at 50 C. in asolution containing by weight 5% ammonia, 0.5 cyanide and 20% sodiumsulfate. Subsequently, the film under tension was heat treated 30minutes at 160 C. in steam at 4 kg./cm. gauge pressure.

When dyed at room temperature using 5% by weight of the film oftartarizine, or acid dyestutf, a brightly yellow-dyed film was obtained.

EXAMPLE 3 Polyvinyl alcohol filaments were prepared by wet spinning. Thefilaments were hot stretched 100% at 235 C. in 2 seconds, and furtherheat treated for 2 seconds at 235 C. The filaments were divided into 2portions, B and C.

Portion B of the filaments was further treated for 1 hour at C. in anaqueous solution containing by weight 0.5% sodium hypochlorite, 0.5sulfuric acid 4 and 15% sodium sulfate. The oxidized portion B filamentswere then treated for 1 hour at 70 C. in an aqueous solution containingby weight 1% ethylenediamine, 0.83% sodium cyanide and 1.73% sodium acidsulfite. The thusly treated portion B filaments contained 0.65% byweight nitrogen.

Both portions B and C of the filaments were treated for 1 hour at 70 C.in an aqueous solution containing by weight 5% formaldehyde, 15 sulfuricacid and 15 sodium sulfate.

Portion B filaments had high water resistance (3.5% shrinkage after 30minutes in 100 C. water), dry tenacity of 4.1 grams/ denier, andexcellent dyeability for acid dyestufi. At C. the filaments absorbed allthe dyestuff Acid Brilliant Scarlet 3R from an aqueous bath containing2% of the dyestuff based on the filament weight.

Portion C of the filaments had a dry tenacity of 5.0 grams/denier andabsorbed no dye under the above dyeing conditions.

EXAMPLE 4 Polyvinyl alcohol filaments were prepared by wet spinning.These filaments were heat treated and formalized by reaction withformaldehyde.

The acetalized filaments were treated for 2 hours at 70 C. in an aqueouschlorite salt solution containing 3 grams/liter efiective chlorine. Thefilaments were then treated for 1 hour at 50 C. in a solution containing22 grams/ liter chloric acid.

The oxidized filaments were treated with amine and cyanide as describedin Example 3.

The resulting filaments were dyed for 1 hour at 80 C. using acid ordirect dyestuffs as described in Examples 1 and 3. Dyed color was muchdeeper when compared to similarly prepared and dyed polyvinyl alcoholfilaments not treated by the invention. Strength of filaments preparedby the invention was about 30% lower than such similarly preparedfilaments.

We claim:

1. The method of improving the dyeability of shaped polyvinyl alcoholarticles which comprises forming a polyvinyl alcohol shaped article,oxidizing said shaped article with an oxidizing agent until 01-20% ofthe hydroxyl groups of said polyvinyl alcohol shaped article areconverted to carbonyl radicals, and reacting the partially oxidizedshaped article at a temperature of from 0-100 C. with a mixtureconsisting of approximately equal molar equivalents of a compoundselected from the group consisting of ammonia, a primary amine, asecondary amine and salts thereof, and of a compound selected from thegroup consisting of hydrogen cyanide, alkali metal cyanides and alkalineearth metal cyanides thereby to produce a shaped polyvinyl alcoholarticle having improved dyeability.

2. The method of improving the dyeability of a polyvinyl alcoholfilament which comprises forming a polyvinyl alcohol filament, oxidizingsaid filament with an oxidizing agent until 01-20% of the hydroxylgroups of said polyvinyl alcohol filament are converted to carbonylradicals, and reacting the partially oxidized filament at a temperatureof from 0l00 C. with a mixture consisting of approximately equal molarequivalents of a compound selected from the group consisting of ammonia,a primary amine, a secondary amine and salts thereof, and of a compoundselected from the group consisting of hydrogen cyanide, alkali metalcyanides, and alkaline earth metal cyanides thereby to produce apolyvinyl alcohol filament having improved dyeability.

3. A polyvinyl alcohol shaped article prepared by the method of claim 1.

4. A polyvinyl alcohol filament prepared by the method of claim 2.

5. The method of improving the dyeability of shaped polyvinyl alcoholarticles which comprises forming a polyvinyl alcohol shaped article,oxidizing said shaped article with an oxidizing agent until 0.1-20% ofthe hydroxyl groups of said polyvinyl alcohol shaped article areconverted to carbonyl radicals, and reacting the partially oxidizedshaped article at a temperature of from 0-l00 C. with a compoundselected from the group consisting of ammonia, a primary amine, asecondary amine and salts thereof, and with a compound selected from thegroup consisting of hydrogen cyanide, alkali metal cyanides and alkalineearth metal cyanides thereby to produce a shaped polyvinyl alcoholarticle having improved dyeability, said compounds being present inamounts sufficient to give said article a nitrogen content of at leastabout 0.4% by weight.

6. The method of improving the dyeability of a polyvinyl alcoholfilament Which comprises forming a polyvinyl alcohol filament, oxidizingsaid filament with an oxidizing agent until 0.l20% of the hydroxylgroups of said polyvinyl alcohol filament are converted to carbonylradicals and reacting the partially oxidized filament at a temperatureof from 0100 C. with a compound selected from the group consisting ofammonia, a primary amine, a secondary amine and salts thereof, and witha compound selected from the group consisting of hydrogen cyanide,alkali metal cyanides, and alkaline earth metal cyanides thereby toproduce a polyvinyl alcohol filament having improved dyeability, saidcompounds being present in amounts sufiicient to give said filament anitrogen content of at least about 0.4% by weight.

7. The method of improving the dyeability of shaped polyvinyl alcoholarticles Which comprises forming a polyvinyl alcohol shaped article,oxidizing said shaped article with an oxidizing agent until 0.140% ofthe hydroxyl groups of said polyvinyl alcohol shaped article areconverted to carbonyl radicals, and reacting the partially oxidizedshaped article at a temperature of from 0l00 C. with a mixtureconsisting of a compound selected from the group consisting of ammonia,a primary amine, a secondary amine and salts thereof, and of a compoundselected from the group consisting of hydrogen cyanide, alkali metalcyanides and alkaline earth metal cyanides thereby to produce a shapedpolyvinyl alcohol article having improved dyeability, said mixture ofcompounds being present in solution in a concentration of l to byweight.

8. The method of improving the dyeability of a polyvinyl alcoholfilament which comprises forming a polyvinyl alcohol filament, oxidizingsaid filament with an oxidizing agent until (L l-20% of the hydroxylgroups of said polyvinyl alcohol filament are converted to carbonylradicals and reacting the partially oxidized filament at a temperatureof from 0- C. with a mixture consisting of a compound selected from thegroup consisting of ammonia, a primary amine, a secondary amine andsalts thereof, and of a compound selected from the group consisting ofhydrogen cyanide, alkali metal cyanides, and alkaline earth metalcyanides thereby to produce a polyvinyl alcohol filament having improveddyeability, said mixture of compounds being present in solution in aconcentration of 1 to 50% by weight.

References Cited in the file of this patent UNITED STATES PATENTS2,143,482 Herrmann Jan. 10, 1939

2. THE METHOD OF IMPROVING THE DYEABILITY OF A POLYVINYL ALCOHOLFILAMENT WHICH COMPRISES FORMING A POLYVINYL ALCOHOL FILAMENT, OXIDIZINGSIAD FILAMENT WITH AN OXIDIZING AGENT UNTIL 0.1-20% OF THE HYDROXYLGROUPS OF SAID POLYVINYL ALCOHOL FILAMENT ARE CONVERTED TO CARBONYLRADICALS, AND REACTING THE PARTIALLY OXIDIZED FILAMENT AT A TEMPERATUREOF FROM 0-100* C. WITH A MIXTURE CONSISTING OF APPROXIMATELY EQUAL MOLAREQUIVALENTS OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF AMMONIA,A PRIMARY AMINE, A SECONDARY AMINE AND SALTS THEREOF, AND OF A COMPOUNDSELECTED FROM THE GROUP CONSISTING OF HYDROGEN CYANIDE, ALKALI METALCYANIDES, AND ALKALINE EARTH METAL CYANIDES THEREBY TO PRODUCE APOLYVINYL ALCOHOL FILAMENT HAVING IMPROVED DYEABILITY.